Accurate diagnosis of a personal level of overload activity is required besides obvious sports and medical applications in stressful situations in order to prevent them. Activity estimation is based on the heart rate and there are two major currently existing heart rate monitors HRM: wrist-based and chest-strap. The very earliest technical solutions for placed over the carpal tunnel wrist pulse monitor with infra-red sensor to pick up the flow of blood therein and radio frequency transmitter to transfer data to a display unit which processes it and displays pulse is cited in U.S. Pat. No. 5,810,736 B1. Quite elegant assembly of wrist pulse monitor with additional piezoelectric sensing elements to eliminate power drain from light emitting diode (LED) and thus more complete noise reduction resulting in improved reading accuracy is proposed in U.S. Pat. No. 5,807,267 B1.
A more sophisticated digital apparatus for detecting arrhythmia by analyzing the continuity of change in pulse waveform is suggested in U.S. Pat. No. 6,095,984 B1. Incorporated into device body motion detection means allow accurate arrhythmia monitoring. This device is developed to a higher degree in U.S. Pat. No. 9,597,004 B2 where advanced technological solution allows two-way communication with a server configured and monitored by a cardiologist in case the user initiated the trigger. Device configuration aims constant heart rate and EKG data collection mostly for diagnostic or intense care purposes. Change of patient condition due to aging or new medication prescription requires new appointments and server update. Moreover, amount of volunteers wishing to be monitored by same cardiologist is limited, while provided service could be expensive.
In U.S. Pat. No. 6,580,942 B1 a chest apparatus for detecting an activity of a human heart operates on proposed circuit which analyzes signals received from the sensors and upon determination that such signals are of electrographic nature, i.e. derived from heart beats, generates an alert. This invention is best for patient monitoring before during and after surgical or medical treatment at the hospital. Such an approach is further advanced in U.S. Pat. No. 9,566,007 B2, which proposes a method that is based on a wearable device for continuously and accurately monitoring ECG and photo-plethysmograph waveform to determine a patient's vital signs. Wrist and chest detectors comprising an analyzer module and blood pressure measuring by pulse transmit time technique require multiple electrodes attached to the patient's chest. This ultimately restricts the movement capability of the user but makes the device a valuable addition to an operation room.
U.S. Pat. No. 6,042,549 B1 is disclosing a personal device for measuring exercise intensity and quantity based on the user pulse, of which limits are computed and set up from preliminary test of maximum oxygen consumption rate. This method and device is rather for professional athletes undergoing intense training and being observed by qualified medical personnel. A method for monitoring a cardiac status during intense exercise is suggested in U.S. Pat. No. 9,566,010 B2 where the proposed algorithm is based on or related to cardiac output cardio force index normalized to cardiac force index at walking. Such training (or self-training) apparatus functionality fully depends on measured acceleration during walking, input weight of the user, and preset maximum activity level. Unfortunately, definitions of neither acceleration during walking with constant speed, nor individual maximum activity level are specified.
U.S. Pat. No. 9,430,615 B2 depicts a device that goes beyond the scope of a wearable monitor. It is a personal phone that plays music or videos configured to utilize measured by two electrodes EKG signals and monitoring method for detecting heart rate anomalies in the background during use and alerting proper authorities in case irregularity occurs. The shortcoming of the device is that it does not take into account the distinctiveness of each user heart rate based on upon their medical history. Therefore, the definition of “anomaly” is not personal and could result in many false positives.
In general, none of the existing heart rate monitoring devices is capable of predicting personal level of dangerous activity and alarm the user of its approach. Moreover, closely related to pulse issues such as continuous blood pressure and metabolic rate estimations have never been a features of any heart rate monitoring device.